Semiconductor components such as a Schottky device are well suited for use in high frequency applications because they have short reverse recovery times and low forward voltages, i.e., low losses. Techniques for increasing the breakdown voltage of a Schottky device have resulted in an increase in its forward voltage and a decrease in its switching speed. Since the forward voltage drop of a Schottky device increases significantly in devices configured to support an increased breakdown voltage, Schottky devices may be limited to applications of less than 300 volts. Power rectifiers that improve the forward voltage drop, reverse leakage current, and switching speed of Schottky contact regions have been described in U.S. Pat. No. 4,982,260 issued to Hsueh-Rong Chang on Jan. 1, 1991. Trench-gated Schottky devices for protecting gate oxide from high electric fields and hot carrier generation have been described in U.S. Pat. No. 6,078,090 issued to Richard K. Williams on Jun. 20, 2000. A drawback with these techniques is that they increase the amount of silicon used to manufacture the Schottky devices, which increases cost. Other drawbacks with Schottky devices are that they have low reverse blocking capabilities, high current leakage characteristics, and high forward voltage drops.
Accordingly, it would be advantageous to have Schottky devices that offer fast switching and soft recovery characteristics with a high voltage blocking capability, a low leakage current, and a low forward voltage drop. It would be of further advantage for the method of manufacturing the Schottky devices to be cost efficient, time efficient, and compatible with Schottky device manufacturing processes.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference characters in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current flow through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain n-channel or p-channel devices, or certain n-type or p-type doped regions, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with embodiments of the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action. The use of the words approximately, about, or substantially means that a value of an element has a parameter that is expected to be very close to a stated value or position. However, as is well known in the art there are always minor variances that prevent the values or positions from being exactly as stated. It is well established in the art that variances of up to about ten percent (10%) (and up to twenty percent (20%) for semiconductor doping concentrations) are regarded as reasonable variances from the ideal goal of exactly as described.